Image forming apparatus having developer supply device

Abstract

In an image forming apparatus having a developing unit for developing an image using toner, a toner box for withholding the toner, and a toner transportation section for transporting the toner withheld in the toner box to the developing unit, the toner transportation section includes a transportation screw portion having formed a spiral blade section on its shaft, a pipe section for controlling a toner transportation route by covering the transportation screw portion of the toner transportation section, and a toner flow suppressing section for suppressing flow of the toner from a space between the transportation screw and pipe section. Consequently, a toner transportation opening formed near the transportation section can be closed, and therefore, the flowing of toner into the developing unit can be controlled or reduced by a simple and inexpensive arrangement.

What is claimed is: 
     
       1. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner transportation means includes: a transportation screw having a supporting shaft and a blade section formed thereon;   a pipe-wise member for covering said transportation screw in a direction along said supporting shaft; and   toner flow suppressing means for suppressing flow of the toner from a space between said transportation screw and said pipe-wise member said toner flow suppressing means being provided to touch at least a part of an inner wall surface of said pipe-wise member in such a manner that contact with said blade section is allowed.     
     
     
       2. The image forming apparatus of claim 1, wherein: said toner flow suppressing means is a toroidal sheet member made of an elastic material and provided to an interior of said pipe-wise member; and   said toroidal sheet member has radial cuts, each extending from a minor diameter end to a major diameter end.   
     
     
       3. The image forming apparatus of claim 1, wherein: said toner flow suppressing means is a cylindrical elastic material which forms a part of said pipe-wise member; and   said elastic material has an inside diameter that allows contact with an exterior portion of the spiral blade section of said transportation screw and a length that allows contact with a pitch of the spiral blade section at least once.   
     
     
       4. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner transportation means includes: a transportation screw having a supporting shaft and a blade section formed thereon; and   a pipe-wise member for covering said transportation screw in a direction along said supporting shaft,   a space between an inside diameter of said pipe-wise member and an exterior of said transportation screw becomes smaller toward a toner replenish opening of said developing device.     
     
     
       5. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner withholding means includes toner stirring means inside, said toner stirring means closing a toner transportation opening formed at said toner withholding means when at least one of an initial setting action and a toner replenishing action is carried out.   
     
     
       6. The image forming apparatus of claim 5, wherein a portion of said toner stirring means that closes said toner transportation opening is a lifting member formed at an end portion of said toner stirring means to lift the toner withheld in said toner withholding means to said toner transportation opening. 
     
     
       7. The image forming apparatus of claim 6, wherein a top end of said lifting member has an arc shape that conforms to a shape of said toner transportation opening. 
     
     
       8. The image forming apparatus of claim 6, wherein said lifting member is of a multi-layer structure having at least a first layer and a second layer, said first layer closing a top surface portion of said toner transportation opening, said second layer touching a wall surface of said toner withholding means at a downstream end in a direction in which replenished toner flows in. 
     
     
       9. The image forming apparatus of claim 8, wherein a sheet of a reinforcing member is placed to a surface and/or a back surface of said lifting member. 
     
     
       10. The image forming apparatus of claim 6, wherein a portion curved to an end opposing a rotational direction of said toner stirring means is formed at a top end portion of said lifting member. 
     
     
       11. The image forming apparatus of claim 6, wherein an elastic member is provided at a side surface of said lifting member. 
     
     
       12. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means having a toner replenish opening for withholding the toner replenished therefrom; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner withholding means includes flowing toner preventing means inside, said flowing toner preventing means being movable to a position to cover said toner transportation means with respect to said toner replenish opening.   
     
     
       13. The image forming apparatus of claim 12, wherein said toner withholding means includes toner stirring means inside, said toner stirring means being placed at a position to give vibrations to said flowing toner preventing means in association with a stirring action. 
     
     
       14. The image forming apparatus of claim 12, wherein: said flowing toner preventing means has at least one valley portion inside said toner withholding means at a portion other than a portion directly above said toner transportation means; and   said valley portion has a discharge opening which is smaller than said toner replenish opening.   
     
     
       15. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device; and   a replenish opening through which the toner is replenished to said toner withholding means, said replenish opening being opened/closed by a lid,   wherein said toner withholding means includes flowing toner preventing means inside, said flowing toner preventing means being movable to close a toner transportation opening formed at said toner transportation means when said lid is open, and to open said toner transportation opening when said lid is closed.   
     
     
       16. The image forming apparatus of claim 15, wherein said flowing toner preventing means is a vibration plate provided inside said toner withholding means. 
     
     
       17. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner withholding means includes flowing toner preventing means, said flowing toner preventing means closing a toner transportation opening provided at said toner transportation means in association with an opening/closing action of a main body exterior portion of said image forming apparatus.   
     
     
       18. The image forming apparatus of claim 17, wherein said flowing toner preventing means includes: a driving rib formed at the main body exterior portion;   a toothed gear driven by said driving rib;   a supporting shaft having said toothed gear at one end and rotating in association with a movement of said toothed gear; and   a transportation opening opening/closing member, provided at the other end of said supporting shaft, for opening/closing said toner transportation opening in association with a rotation of said supporting shaft.   
     
     
       19. The image forming apparatus of claim 17, wherein said flowing toner preventing means is provided in such a manner to move with respect to said toner transportation means so as to close said toner transportation opening at an end portion thereof, said flowing toner preventing means being a transportation screw provided to said transportation means. 
     
     
       20. An image forming apparatus comprising: a developing device for developing an image of an original document on a recording medium by using toner;   toner withholding means for withholding the toner; and   toner transportation means for transporting the toner withheld in said toner withholding means to said developing device,   wherein said toner transportation means includes: a transportation screw having a supporting shaft and a blade section formed thereon;   a pipe-wise member for covering said transportation screw in a direction along said supporting shaft; and   toner flow suppressing means for suppressing flow of the toner from a space between said transportation screw and said pipe-wise member, said toner flow suppressing means being provided to said transportation screw along said blade section in such a manner that contact with an inner wall of said pipe-wise member is allowed.     
     
     
       21. The image forming apparatus of claim 20, wherein: said toner flow suppressing means is an elastic member attached along an arc of the spiral blade section of said transportation screw; and   said elastic member is allowed to contact an inner surface of said pipe-wise member when said transportation screw rotates.   
     
     
       22. The image forming apparatus of claim 20, wherein: said toner flow suppressing means is a brush member attached along an arc of the spiral blade section of said transportation screw; and   said brush member is allowed to touch an inner surface of said pipe-wise member when said transportation screw rotates.   
     
     
       23. The image forming apparatus of claim 22, further comprising a groove portion at a top end of the spiral blade section of said transportation screw, said brush member being attached to said transportation screw by being fitted into said groove portion. 
     
     
       24. The image forming apparatus of claim 20, wherein: said toner flow suppressing means is a spring member wrapped around the supporting shaft of said transportation screw along the spiral blade section thereof; and   said spring member is wrapped around the supporting shaft in a length at least as long as a pitch of the spiral blade section.   
     
     
       25. The image forming apparatus of claim 24, wherein: as fixing means for fixedly wrapping said spring member around the supporting shaft of said transportation screw, a linear member which can be fixedly wrapped around the supporting shaft along the spiral blade section of said transportation screw is used; and   said linear member fixes said spring member by being fitted through said spring member first and thence wrapped around the supporting shaft.   
     
     
       26. The image forming apparatus of claim 25, wherein said spring member is fixed by said linear member on and along only one of surfaces of the spiral blade section of said transportation screw.